Wang Kanglin, Mittleman Daniel M
Department of Electrical and Computer Engineering, MS 366, Rice University, Houston, Texas 77251-1892, USA.
Nature. 2004 Nov 18;432(7015):376-9. doi: 10.1038/nature03040.
Sources and systems for far-infrared or terahertz (1 THz = 10(12) Hz) radiation have received extensive attention in recent years, with applications in sensing, imaging and spectroscopy. Terahertz radiation bridges the gap between the microwave and optical regimes, and offers significant scientific and technological potential in many fields. However, waveguiding in this intermediate spectral region still remains a challenge. Neither conventional metal waveguides for microwave radiation, nor dielectric fibres for visible and near-infrared radiation can be used to guide terahertz waves over a long distance, owing to the high loss from the finite conductivity of metals or the high absorption coefficient of dielectric materials in this spectral range. Furthermore, the extensive use of broadband pulses in the terahertz regime imposes an additional constraint of low dispersion, which is necessary for compatibility with spectroscopic applications. Here we show how a simple waveguide, namely a bare metal wire, can be used to transport terahertz pulses with virtually no dispersion, low attenuation, and with remarkable structural simplicity. As an example of this new waveguiding structure, we demonstrate an endoscope for terahertz pulses.
近年来，用于远红外或太赫兹（1太赫兹 = 10¹²赫兹）辐射的源和系统受到了广泛关注，其应用于传感、成像和光谱学领域。太赫兹辐射填补了微波和光学频段之间的空白，并且在许多领域具有巨大的科学和技术潜力。然而，在这个中间光谱区域进行波导传输仍然是一个挑战。由于金属有限电导率导致的高损耗或者该光谱范围内介电材料的高吸收系数，用于微波辐射的传统金属波导以及用于可见光和近红外辐射的介电光纤都无法用于长距离引导太赫兹波。此外，太赫兹频段中宽带脉冲的广泛使用对低色散提出了额外的要求，这对于与光谱应用的兼容性来说是必要的。在此，我们展示了一种简单的波导，即裸金属线，如何能够用于传输太赫兹脉冲，几乎没有色散、低衰减，并且结构极其简单。作为这种新波导结构的一个示例，我们展示了一种用于太赫兹脉冲的内窥镜。
